The present invention relates to a chuck for transporting to a target place a work piece gripped by a aplurality of jaw members to be opened or closed freely, more specifically, it relates to a chuck with a position detecting function capable of detecting the operating position of the jaw members.
A chuck storing an air cylinder utilizing the air pressure, a linear motor utilizing the electromagnetic force, or the like, as the driving source for gripping a work piece by opening or closing a plurality of jaw members by the function of the air cylinder or the linear motor has been well known conventionally.
As this kind of a chuck, there is one provided with a position detecting device utilizing the magnetism for detecting the opening or closing position of the jaw members. The position detecting device comprises a permanent magnet mounted on a driving rod of the air cylinder or the linear motor, or mounted on the jaw members, and a magnetic sensor mounted on the casing side so that the opening or closing position of the jaw members can be detected according to the detection of the permanent magnet by the magnetic sensor.
However, since the above-mentioned conventional position detecting device is of a system of detecting the permanent magnet mounted on the driving rod or the jaw members, only the opening or closing stroke end positions of the jaw members, that is, the position with the jaw members gripping a work piece or with the jaw members opened can be detected but the operating position of the jaw members has never been detected for all the strokes.
A main technological task of the present invention is to provide a chuck with a position detecting function capable of detecting the operating position of a jaw member for all the stroke.
Another technological task of the present invention is to provide a chuck with a reasonable designing structure with a driving part for opening or closing a jaw member, and a position detecting part for detecting the operating position of the jaw member assembled in a casing efficiently with other mechanisms without causing enlargement.
A still another technological task of the present invention is to obtain a stable opening or closing operation in the chuck by preventing the opening or closing operation of the jaw member from becoming unsmooth by assembling the driving part and the position detecting part bonded organically in the casing.
In order to solve the above-mentioned problem, according to the present invention, a chuck with a position detecting function characterized in comprising a plurality of jaw members provided on a casing, to be opened or closed freely; a driving part provided on the base end part side in the axial direction of the casing, positioned on either right or left one half part side of the casing; a position detecting part for detecting the operating position of the jaw members for all the stroke according to a scale displaced synchronous with a driving rod of the driving part provided at a right and left position adjacent to the driving part on the base end part side of the casing, and a reader for reading the calibration engraved on the scale; a linear guide mechanism provided between the driving part and the position detecting part for guiding the linear reciprocal movement of the scale; and a converting mechanism provided between the jaw members and the driving part for converting the linear reciprocal motion of the driving rod into the opening or closing operation of the jaw members can be provided.
In the chuck with the above-mentioned configuration, the jaw members are opened or closed according to the movement of the driving rod of the driving part so as to grip or release a work piece. At the time, since the calibration on the scale moving synchronously with the driving rod is read out continuously by the reader, the operating position of the jaw members is detected for all the opening and closing stroke.
Here, since the driving part, the position detecting part, and the linear guide mechanism are assembled efficiently in the casing at right and left adjacent positions so as to be stored within the width of the casing, that is, in the installation domain of the jaw members, the chuck cannot be enlarged by the addition of the position detecting part, the linear guide mechanism, or the like. Besides, since the linear guide mechanism is provided between the driving part and the position detecting part, the scale can be displaced stably in the state synchronous with the driving rod as well as the movement of the driving rod can be transmitted certainly to the jaw members via the converting mechanism so as to open or close the jaw members stably.
According to a concrete embodiment of the present invention, the converting mechanism comprises two levers for opening or closing the jaw members by swaying, and a relay plate for interlocking the levers with the driving rod, wherein the relay plate is provided with a relay shaft positioned on the chuck center, with the base end part of each lever pivoted on the relay shaft rotatably by a common shaft, and the relay plate is interlocked with the driving rod and a scale supporting member for supporting the scale, displaceably together to different positions with the relay shaft interposed therebetween via the relay plate.
According to another concrete embodiment of the present invention, the linear guide mechanism comprises a guide rail and a slider slidable along the guide rail, wherein the guide rail is fixed on the outer wall of the driving part, parallel with the driving rod, and the slider is mounted on the scale side.
In the case the driving rod is interlocked with the relay plate, in order to prevent twisting, it is preferable to interlock by a floating method with a collar interposed so as to provide a slight freedom therebetween in the tilt direction.
According to an embodiment of the present invention, the driving part includes a linear motor to be operated by an electromagnetic force such that the driving rod is moved forward or backward by the linear motor.
The linear motor comprises a cylindrical magnetic frame made of a magnetic member, a non-magnetic member bobbin stored in the magnetic frame, a plurality of magnetic coils wound around on the bobbin, and a piston assembly inserted in the bobbin slidably in the axial direction, interlocked with the driving rod, wherein the piston assembly is formed by mounting a plurality of circular permanent magnets on the outer periphery of the driving rod with a yoke interposed therebetween.
According to another embodiment of the present invention, the driving part includes a fluid pressure cylinder mechanism to be operated by the fluid pressure such that the driving rod is moved forward or backward by the fluid pressure cylinder mechanism.